1. Field of the Invention
This invention concerns a recognition device, a bonding device, and a circuit device manufacturing method, and in particular concerns the improvement of the precision of recognition by a recognition device, the improvement of the precision of bonding by a bonding device, and a circuit device manufacturing method that uses such a recognition device and bonding device.
2. Description of the Related Art
Priorly with semiconductor devices, wire bonding to mounting parts formed on a lead frame was performed according to each mounting part, and as an embodiment therefor, a recognition device and bonding device for such wire bonding is disclosed for example in Japanese Unexamined Patent Publication No. Sho-63-29535.
As shown in FIG. 17, a transistor lead frame 2, to which a chip 10 is attached, is set on a heating block part 1. A bonding arm 3 is disposed above lead frame 2 on heating block 1 and a capillary 4 is disposed at the tip of bonding arm 3. A wire 5 is disposed in this capillary 4 and a torch 6, for forming a ball from wire 5, is disposed near capillary 4.
This thermocompression type bonding device is provided with a wire bonding position recognition part 7 and a bonding head driving part 8 as well as with a local heating device 9, which is set to operate in linkage with the operation of bonding head driving part 8 in the X and Y directions and is for heating the bonding part locally. A laser beam device may for example be used as this local heating device 9.
The operations shall now be described. Bonding head driving part 8 is made to move, as programmed in advance in accordance with information from wire bonding position recognition part 7, to lead frame 2 that has been heated by heating block 1, local heating device 9 is made to operate just during the bonding process to perform ball bonding while compensating for inadequate heat on chip 10, capillary 4 is thereafter moved to the lead frame 2 side, local heating device 9 is made to operate again just during the bonding process to perform stitch bonding while compensating for inadequate heat at the lead frame 2 side, and then torch 6 is made to form a ball part at the tip of a wire 5 that has been cut.
Ball bonding is then performed on the other electrode of chip 10 while making local heating device 9 operate just during bonding to compensate for inadequate heat at chip 10, capillary 4 is thereafter moved to the lead frame side, local heating device 9 is made to operate again just during the bonding process to perform stitch bonding while compensating for inadequate heat at the lead frame side, and then torch 6 is made to form a ball part at the tip of a wire 5 that has been cut. Since bonding is thus performed while compensating for inadequate heat at the bonding part, a high quality wire bond is obtained. A wire bond of even higher quality can be obtained by using ultrasonic waves in combination.
Also though the case of a transistor chip was described with the above-described embodiment, this invention is not limited thereto and the chip may be a diode, IC, etc., and the invention can thus be applied as a wire bonder for any semiconductor device.
In the case where mounting parts are formed on a completely punched lead frame 2 as has been described above, just the mounting parts need to be heated, for example, to approximately 250° C. during wire bonding. That is, since the entirety of lead frame 2 is not constantly in a high temperature state and wire bonding could be performed by partial heating, there are no problems of erroneous recognition, degradation of recognition conditions, etc., with the bonding device and recognition device in the above-described example.
Though details shall be given with the description of an embodiment of the present invention, in the case where a cluster block, having a plurality of mounting parts within a small area, is formed on a conductive foil, lead frame, etc., the conductive foil or lead frame, etc., will be kept at a high temperature state until all of the wire bonding processes for a single cluster block has been completed. There was thus the problem that the conductive foil or lead frame, etc., with the cluster block becomes oxidized due to being placed in the abovementioned high temperature state over a long period of time.
The abovementioned oxidation of the lead frame, etc., may be prevented by placing the lead frame in the high temperature state in a space filled with an inert gas, such as nitrogen gas. However, in order to form this space, an inert-gas-filled space must be formed above the working base on which the lead frame is set and furthermore, a working hole for recognition and wire bonding must be formed above this space. In this case, the inert gas becomes heated to a high temperature within the space and, in the process of escaping to the exterior from the working hole, gives rise to a fluctuation (shimmer) due to the temperature difference with room temperature. This fluctuation invades the recognition region and causes erroneous recognition by the recognition camera, thus leading to lack of precision of recognition of highly integrated, fine, conductive patterns.